scholarly journals BTB-TAZ domain protein MdBT2 modulates malate accumulation by targeting a bHLH transcription factor for degradation in response to nitrate

2019 ◽  
Author(s):  
Quan-Yan Zhang ◽  
Kai-Di Gu ◽  
Lailiang Cheng ◽  
Jia-Hui Wang ◽  
Jian-Qiang Yu ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Underlying Mechanism ◽  
Apple Fruit ◽  
26S Proteasome ◽  
Bhlh Transcription Factor ◽  
Atpase Gene ◽  
Vacuolar Acidification ◽  
Vacuolar Ph

AbstractExcessive application of nitrate, an essential macronutrient and a signal regulating diverse physiological processes, decreases malate accumulation in apple fruit, but the underlying mechanism remains poorly understood. Here, we show that an apple BTB/TAZ protein MdBT2 is involved in regulating malate accumulation and vacuolar pH in response to nitrate. In vitro and in vivo assays indicate that MdBT2 interacts directly with and ubiquitinates a bHLH transcription factor, MdCIbHLH1, via the ubiquitin/26S proteasome pathway in response to nitrate. This ubiquitination results in the degradation of MdCIbHLH1 protein and reduces the transcription of MdCIbHLH1-targeted genes involved in malate accumulation and vacuolar acidification including MdVHA-A encoding a vacuolar H+-ATPase gene, and MdVHP1 encoding a vacuolar H+-pyrophosphatase gene, as well as MdALMT9 encoding a aluminum-activated malate transporter gene. A series of transgenic analyses in apple materials including fruits, plantlets and calli demonstrate that MdBT2 controls nitrate-mediated malate accumulation and vacuolar pH at least partially, if not completely, via regulating the MdCIbHLH1 protein level. Taken together, these findings reveal that MdBT2 regulates the stability of MdCIbHLH1 via ubiquitination in response to nitrate, which in succession transcriptionally reduces the expression of malate-associated genes, thereby controlling malate accumulation and vacuolar acidification in apples under high nitrate supply.

scholarly journals Degradation of Myogenic Transcription Factor MyoD by the Ubiquitin Pathway In Vivo and In Vitro: Regulation by Specific DNA Binding

1998 ◽  
Vol 18 (10) ◽  
pp. 5670-5677 ◽  
Author(s):  
Ossama Abu Hatoum ◽  
Shlomit Gross-Mesilaty ◽  
Kristin Breitschopf ◽  
Aviad Hoffman ◽  
Hedva Gonen ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Dna Binding ◽  
Specific Inhibitor ◽  
Inhibitory Effect ◽  
26S Proteasome ◽  
Intact Cells ◽  
Free System ◽  
Ubiquitin System

ABSTRACT MyoD is a tissue-specific transcriptional activator that acts as a master switch for skeletal muscle differentiation. Its activity is induced during the transition from proliferating, nondifferentiated myoblasts to resting, well-differentiated myotubes. Like many other transcriptional regulators, it is a short-lived protein; however, the targeting proteolytic pathway and the underlying regulatory mechanisms involved in the process have remained obscure. It has recently been shown that many short-lived regulatory proteins are degraded by the ubiquitin system. Degradation of a protein by the ubiquitin system proceeds via two distinct and successive steps, conjugation of multiple molecules of ubiquitin to the target protein and degradation of the tagged substrate by the 26S proteasome. Here we show that MyoD is degraded by the ubiquitin system both in vivo and in vitro. In intact cells, the degradation is inhibited by lactacystin, a specific inhibitor of the 26S proteasome. Inhibition is accompanied by accumulation of high-molecular-mass MyoD-ubiquitin conjugates. In a cell-free system, the proteolytic process requires both ATP and ubiquitin and, like the in vivo process, is preceded by formation of ubiquitin conjugates of the transcription factor. Interestingly, the process is inhibited by the specific DNA sequence to which MyoD binds: conjugation and degradation of a MyoD mutant protein which lacks the DNA-binding domain are not inhibited. The inhibitory effect of the DNA requires the formation of a complex between the DNA and the MyoD protein. Id1, which inhibits the binding of MyoD complexes to DNA, abrogates the effect of DNA on stabilization of the protein.

scholarly journals Transcription Factor E2F1 Knockout Promotes Mice White Adipose Tissue Browning Through Autophagy Inhibition

2021 ◽  
Vol 12 ◽  
Author(s):  
Mingchen Xiong ◽  
Weijie Hu ◽  
Yufang Tan ◽  
Honghao Yu ◽  
Qi Zhang ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Adipose Tissue ◽  
White Adipose Tissue ◽  
Uncoupling Protein ◽  
Underlying Mechanism ◽  
Metabolic Complications ◽  
Autophagy Inhibition ◽  
Transcription Factor E2f1

Obesity is associated with energy metabolic disturbance and is caused by long-term excessive energy storage in white adipose tissue (WAT). The WAT browning potentially reduces excessive energy accumulation, contributing an attractive target to combat obesity. As a pivotal regulator of cell growth, the transcription factor E2F1 activity dysregulation leads to metabolic complications. The regulatory effect and underlying mechanism of E2F1 knockout on WAT browning, have not been fully elucidated. To address this issue, in this study, the in vivo adipose morphology, mitochondria quantities, uncoupling protein 1 (UCP-1), autophagy-related genes in WAT of wild-type (WT) and E2F1–/– mice were detected. Furthermore, we evaluated the UCP-1, and autophagy-related gene expression in WT and E2F1–/– adipocyte in vitro. The results demonstrated that E2F1 knockout could increase mitochondria and UCP-1 expression in WAT through autophagy suppression in mice, thus promoting WAT browning. Besides, adipocytes lacking E2F1 showed upregulated UCP-1 and downregulated autophagy-related genes expression in vitro. These results verified that E2F1 knockout exerted effects on inducing mice WAT browning through autophagy inhibition in vivo and in vitro. These findings regarding the molecular mechanism of E2F1-modulated autophagy in controlling WAT plasticity, provide a novel insight into the functional network with the potential therapeutic application against obesity.

scholarly journals The N terminus of Ascl1 underlies differing proneural activity of mouse and Xenopus Ascl1 proteins

2018 ◽  
Vol 3 ◽  
pp. 125 ◽  
Author(s):  
Laura J.A. Hardwick ◽  
Anna Philpott
Keyword(s):  
Transcription Factor ◽  
Bhlh Transcription Factor ◽  
Protein Accumulation ◽  
Primary Neuron ◽  
Helix Loop Helix ◽  
N Terminus ◽  
Specific Regulation ◽  
Species Specific

The proneural basic-helix-loop-helix (bHLH) transcription factor Ascl1 is a master regulator of neurogenesis in both central and peripheral nervous systems in vivo, and is a central driver of neuronal reprogramming in vitro. Over the last three decades, assaying primary neuron formation in Xenopus embryos in response to transcription factor overexpression has contributed to our understanding of the roles and regulation of proneural proteins like Ascl1, with homologues from different species usually exhibiting similar functional effects. Here we demonstrate that the mouse Ascl1 protein is twice as active as the Xenopus protein in inducing neural-β-tubulin expression in Xenopus embryos, despite there being little difference in protein accumulation or ability to undergo phosphorylation, two properties known to influence Ascl1 function. This superior activity of the mouse compared to the Xenopus protein is dependent on the presence of the non-conserved N terminal region of the protein, and indicates species-specific regulation that may necessitate care when interpreting results in cross-species experiments.

scholarly journals Disruption of CK2β in Embryonic Neural Stem Cells Compromises Proliferation and Oligodendrogenesis in the Mouse Telencephalon

2010 ◽  
Vol 30 (11) ◽  
pp. 2737-2749 ◽  
Author(s):  
Emmanuelle Huillard ◽  
Léa Ziercher ◽  
Olivier Blond ◽  
Michael Wong ◽  
Jean-Christophe Deloulme ◽  
...  
Keyword(s):  
Transcription Factor ◽  
System Development ◽  
Nervous System Development ◽  
Conditional Knockout ◽  
Regulatory Subunit ◽  
Bhlh Transcription Factor ◽  
Helix Loop Helix ◽  
Proliferation And Differentiation

ABSTRACT Genetic programs that govern neural stem/progenitor cell (NSC) proliferation and differentiation are dependent on extracellular cues and a network of transcription factors, which can be regulated posttranslationally by phosphorylation. However, little is known about the kinase-dependent pathways regulating NSC maintenance and oligodendrocyte development. We used a conditional knockout approach to target the murine regulatory subunit (beta) of protein kinase casein kinase 2 (CK2β) in embryonic neural progenitors. Loss of CK2β leads to defects in proliferation and differentiation of embryonic NSCs. We establish CK2β as a key positive regulator for the development of oligodendrocyte precursor cells (OPCs), both in vivo and in vitro. We show that CK2β directly interacts with the basic helix-loop-helix (bHLH) transcription factor Olig2, a critical modulator of OPC development, and activates the CK2-dependent phosphorylation of its serine-threonine-rich (STR) domain. Finally, we reveal that the CK2-targeted STR domain is required for the oligodendroglial function of Olig2. These findings suggest that CK2 may control oligodendrogenesis, in part, by regulating the activity of the lineage-specific transcription factor Olig2. Thus, CK2β appears to play an essential and uncompensated role in central nervous system development.

scholarly journals Transcription Factor Runx1 Activates Opn to Promote Tumor Progression in Head and Neck Cancer

2020 ◽  
Author(s):  
Kai Liu ◽  
Huiying Hu ◽  
Huanyu Jiang ◽  
Haidong Zhang ◽  
Shanchun Gong ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Head And Neck ◽  
Therapeutic Potential ◽  
Underlying Mechanism ◽  
Mapk Signaling ◽  
Luciferase Reporter ◽  
Metastatic Progression ◽  
Related Transcription Factor

Abstract Background:Metastatic progression remains a major burden for head and neck squamous cell carcinoma (HNSCC). Runt-related transcription factor 1 (RUNX1)has been reported to be associated with an aggressive phenotype in several cancers. However, the precise roles of RUNX1 underlying the metastaticprogression of HNSCC remain largely unknown.Methods:RUNX1 expression levels in HNSCC cells and tissues were detected by quantitative real-time PCR (qPCR), Western blottingand immunohistochemistry (IHC). In vitro and in vivo assays were performed to investigate the function of RUNX1 in the metastatic phenotype and the tumorigenic capability of HNSCC cells. Luciferase reporter and chromatin immunoprecipitation (ChIP)-qPCR assays were performed to determine the underlying mechanism of RUNX1-mediated HNSCC aggressiveness.Results:RUNX1 was increased with disease progression in patients withHNSCC.Furthermore, we found that silencing ofRUNX1 significantly decelerated the malignant progression of HNSCC cells and reduced Osteopontin (OPN) expression in vitro, and weakened the tumorigenicityof HNSCC cells in vivo. Mechanistically, we demonstrated that RUNX1 played an important role in activating MAPK signaling by directly binding to the promoter of OPN.Conclusions: Our results provide new insight into the mechanisms underlying the facilitate metastasisability of RUNX1and reveal the therapeutic potential of targeting RUNX1 in HNSCC.

scholarly journals MESP2 Binds Competitively To TCF4 to Suppress Gastric Cancer Progression By Regulating The SKP2/p27 Axis

2021 ◽  
Author(s):  
Lingjun Ge ◽  
Gaichao Zhao ◽  
Chao Lan ◽  
Ruoyue Tan ◽  
Shengjun Geng ◽  
...  
Keyword(s):  
Gastric Cancer ◽  
Transcription Factor ◽  
Molecular Mechanisms ◽  
Tumor Formation ◽  
Migration And Invasion ◽  
Bhlh Transcription Factor ◽  
Beta Catenin ◽  
Incidence And Mortality

Abstract Background: Gastric cancer (GC) is a major cause of human deaths worldwide, and is notorious for its high incidence and mortality rates. Mesoderm Posterior Basic Helix-loop-helix (bHLH) transcription factor 2 (MESP2) acts as a transcription factor with a conserved bHLH domain. However, whether MESP2 contributes to tumorigenesis and its potential molecular mechanisms, remain unexplored.Methods: Immunohistochemistry was used to examine MESP2 expression in clinical gastric tissues. In vitro cell proliferation, migration, and invasion assays were used to investigate the effects of MESP2 on gastric cells progress. Expression microarray profiling，co-immunoprecipitation and chromatin immunoprecipitation were used to explore the potential molecular mechanisms of MESP2 on tumorigenesis. Subcutaneous tumor formation and orthotopic implantation assays were performed in NOD/SCID mice to confirm the effects of MESP2 on gastric growth and metastasis in vivo. Results: Noticeably, MESP2 expression levels are decreased in GC tissues and cell lines compared to those in normal tissue. Further, in vitro and in vivo experiments have confirmed that MESP2 overexpression suppresses GC cell growth, migration, and invasion, whereas MESP2 knockdown results in the exact opposite. In addition, MESP2 binds to transcription factor 7-like 2 (TCF7L2/TCF4) to inhibit the activation of the TCF4/beta-catenin transcriptional complex, decrease the occupancy of the complex on the S-phase kinase Associated Protein 2 (SKP2) promoter, and promote p27 accumulation. MESP2 knockdown facilitated tumorigenesis, which was partially suppressed by SKP2 knockdown. Conclusions: Our findings demonstrate that MESP2 binds competitively to TCF4 to suppress GC progression by regulating the SKP2/p27 axis, thus offering a potential therapeutic strategy for future treatment.

Subnuclear compartmentalization of sequence-specific transcription factors and regulation of eukaryotic gene expression

2005 ◽  
Vol 83 (4) ◽  
pp. 535-547 ◽  
Author(s):  
Gareth N Corry ◽  
D Alan Underhill
Keyword(s):  
Gene Expression ◽  
Transcription Factor ◽  
Transcription Factors ◽  
Transcriptional Activation ◽  
Current Knowledge ◽  
Nuclear Architecture ◽  
Subnuclear Localization ◽  
Modular Structures

To date, the majority of the research regarding eukaryotic transcription factors has focused on characterizing their function primarily through in vitro methods. These studies have revealed that transcription factors are essentially modular structures, containing separate regions that participate in such activities as DNA binding, protein–protein interaction, and transcriptional activation or repression. To fully comprehend the behavior of a given transcription factor, however, these domains must be analyzed in the context of the entire protein, and in certain cases the context of a multiprotein complex. Furthermore, it must be appreciated that transcription factors function in the nucleus, where they must contend with a variety of factors, including the nuclear architecture, chromatin domains, chromosome territories, and cell-cycle-associated processes. Recent examinations of transcription factors in the nucleus have clarified the behavior of these proteins in vivo and have increased our understanding of how gene expression is regulated in eukaryotes. Here, we review the current knowledge regarding sequence-specific transcription factor compartmentalization within the nucleus and discuss its impact on the regulation of such processes as activation or repression of gene expression and interaction with coregulatory factors.Key words: transcription, subnuclear localization, chromatin, gene expression, nuclear architecture.

scholarly journals GCH1 induces immunosuppression through metabolic reprogramming and IDO1 upregulation in triple-negative breast cancer

2021 ◽  
Vol 9 (7) ◽  
pp. e002383
Author(s):  
Jin-Li Wei ◽  
Si-Yu Wu ◽  
Yun-Song Yang ◽  
Yi Xiao ◽  
Xi Jin ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Triple Negative Breast Cancer ◽  
Triple Negative ◽  
Molecular Taxonomy ◽  
Underlying Mechanism ◽  
Metabolic Reprogramming ◽  
Sequencing Data ◽  
Aryl Hydrocarbon

PurposeRegulatory T cells (Tregs) heavily infiltrate triple-negative breast cancer (TNBC), and their accumulation is affected by the metabolic reprogramming in cancer cells. In the present study, we sought to identify cancer cell-intrinsic metabolic modulators correlating with Tregs infiltration in TNBC.Experimental designUsing the RNA-sequencing data from our institute (n=360) and the Molecular Taxonomy of Breast Cancer International Consortium TNBC cohort (n=320), we calculated the abundance of Tregs in each sample and evaluated the correlation between gene expression levels and Tregs infiltration. Then, in vivo and in vitro experiments were performed to verify the correlation and explore the underlying mechanism.ResultsWe revealed that GTP cyclohydrolase 1 (GCH1) expression was positively correlated with Tregs infiltration and high GCH1 expression was associated with reduced overall survival in TNBC. In vivo and in vitro experiments showed that GCH1 increased Tregs infiltration, decreased apoptosis, and elevated the programmed cell death-1 (PD-1)-positive fraction. Metabolomics analysis indicated that GCH1 overexpression reprogrammed tryptophan metabolism, resulting in L-5-hydroxytryptophan (5-HTP) accumulation in the cytoplasm accompanied by kynurenine accumulation and tryptophan reduction in the supernatant. Subsequently, aryl hydrocarbon receptor, activated by 5-HTP, bound to the promoter of indoleamine 2,3-dioxygenase 1 (IDO1) and thus enhanced the transcription of IDO1. Furthermore, the inhibition of GCH1 by 2,4-diamino-6-hydroxypyrimidine (DAHP) decreased IDO1 expression, attenuated tumor growth, and enhanced the tumor response to PD-1 blockade immunotherapy.ConclusionsTumor-cell-intrinsic GCH1 induced immunosuppression through metabolic reprogramming and IDO1 upregulation in TNBC. Inhibition of GCH1 by DAHP serves as a potential immunometabolic strategy in TNBC.

scholarly journals Integrin α3β1 Promotes Invasive and Metastatic Properties of Breast Cancer Cells through Induction of the Brn-2 Transcription Factor

Cancers ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 480
Author(s):  
Rakshitha Pandulal Miskin ◽  
Janine S. A. Warren ◽  
Abibatou Ndoye ◽  
Lei Wu ◽  
John M. Lamar ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Transcription Factor ◽  
Cancer Cells ◽  
Cell Invasion ◽  
Breast Cancer Cells ◽  
Gene Promoter ◽  
Akt Inhibitor ◽  
Integrin Α3β1

In the current study, we demonstrate that integrin α3β1 promotes invasive and metastatic traits of triple-negative breast cancer (TNBC) cells through induction of the transcription factor, Brain-2 (Brn-2). We show that RNAi-mediated suppression of α3β1 in MDA-MB-231 cells caused reduced expression of Brn-2 mRNA and protein and reduced activity of the BRN2 gene promoter. In addition, RNAi-targeting of Brn-2 in MDA-MB-231 cells decreased invasion in vitro and lung colonization in vivo, and exogenous Brn-2 expression partially restored invasion to cells in which α3β1 was suppressed. α3β1 promoted phosphorylation of Akt in MDA-MB-231 cells, and treatment of these cells with a pharmacological Akt inhibitor (MK-2206) reduced both Brn-2 expression and cell invasion, indicating that α3β1-Akt signaling contributes to Brn-2 induction. Analysis of RNAseq data from patients with invasive breast carcinoma revealed that high BRN2 expression correlates with poor survival. Moreover, high BRN2 expression positively correlates with high ITGA3 expression in basal-like breast cancer, which is consistent with our experimental findings that α3β1 induces Brn-2 in TNBC cells. Together, our study demonstrates a pro-invasive/pro-metastatic role for Brn-2 in breast cancer cells and identifies a role for integrin α3β1 in regulating Brn-2 expression, thereby revealing a novel mechanism of integrin-dependent breast cancer cell invasion.

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